The purpose of this application is to establish a post-doctoral training program in the Mental Retardation and Developmental Disabilities (MRDD) Research Center at the Children's Research Institute, of Children's National Medical Center (CNMC) in Washington, D.C. The focus of this program will be on five areas of inquiry associated with MRDD: autism, learning disabilities (developmental dyslexia), traumatic brain injury, epilepsy, and urea cycle disorders. This will be a multidisciplinary effort that draws on 14 faculty preceptors in the areas of neuroscience, neurobehavioral science and genetics from seven Departments at CNMC and Georgetown University School of Medicine. CNMC is particularly well positioned to lead this program, based on: i) its strengths in basic, translational and clinical research, and in mentorship in all the proposed areas of inquiry;ii) its established strong collaborations with Georgetown University, and iii) its leading role in a number of NIH Center Grants focusing on conditions causing MRDD. We propose to enter 2 postdoctoral trainees (MD and PhD) per year in the 3 year training program. A unique aspect of the training will be that each area of inquiry will have genetic, neuroscience and neurobehavioral components, and each fellow will chose a mentor's laboratory that focuses on one of these areas but will rotate through each component to acquire Interdisciplinary training in the specific disorder being studied. The objectives of the program are to encourage MD's to develop as researchers in the field of MRDD and to stimulate greater participation of promising PhD researchers in this area. Each trainee will be carefully mentored through the program to ensure that he/she fully exploits the range of opportunities of the program.